This is still a Beta feature, and not all authors with paperbacks in KDP Print can use it yet.
Launched into a closed beta last summer, KDP Print is Amazon’s solution to all the indie authors that release ebooks but not print editions. It is a more limited version of Amazon’s POD service, Createspace, and it’s missing a lot of features.
Until today, one option it lacked was a way for authors to order copies of their POD books in wholesale volume. According to a number of reports on KBoards, Amazon has sent an email to authors announcing the new feature: